I've recently visited a local Sporting Goods shop (Sports Basement) and saw the Hiker Pro on display there. After hovering around it for a while a store associate came over and explained to me how it works and highly recommending it for longer backpacking trips.
I mostly do day trips and need something small for emergency so Katadyn Hiker Pro seemed a bit too much. But this whole discussion turned up something I think I've been looking for all along - Steripen. There is a cool looking Steripen Defender which is probably an overkill "military grade" costing twice the price of an Adventurer Opti.